Globalization of the integrated circuit (IC) manufacturing industry has led to supply chain integrity becoming a potential concern, particularly for high-consequence systems. Supply chain integrity may be compromised leading to components being counterfeited and/or subverted.
Counterfeit ICs may have been “knowingly misrepresented”; that is, they may have been marked as being fabricated at a particular fabrication facility, but in reality may have been fabricated at some other fabrication facility. For example, a customer may set forth an order for a relatively large number of ICs, and a provider may indicate to the customer that the ICs will be made at a particular fabrication facility. The provider, however, may sub-contract with a second (less expensive) provider, such that the customer is provided with ICs that perform the same function, while unbeknownst to the customer the ICs are fabricated by the second provider. There are several reasons this may be undesirable: 1) the second provider may produce ICs at lower quality than the first provider (e.g., the ICs may have a shorter lifespan); 2) the second provider may attempt to modify the design of the IC to place malicious functionality in the IC (e.g., capture credit card data and transmit it to a malicious entity); 3) the second provider may be located in a country that is embargoed by a country of the customer, thereby putting the customer at risk, etc.
As noted above, subverted ICs may have been modified for a malicious purpose during some part of the fabrication process (known as hardware Trojans) or have been wholly substituted with a “compatible” part. These modifications could be made with or without changes to the IC layout and could be used to transmit information, modify specifications of ICs (e.g., operating temperature range), or modify logical function of the IC.
Existing methods to detect counterfeit ICs include addition of special markings such as holographic stickers, transmission electron microscopy (TEM) and X-ray inspection, destructive chemical composition tests, and side-channel measurements. Holograms and other special markings are hard-to-replicate items that are attached to a product. However, holograms might not be trustworthy because they can be overbuilt, and they can be removed and re-attached. Methods of microscopic inspection are useful for finding gross differences in the geometry and composition of a part. These existing methods can be expensive, time-consuming and may generate false negatives.